Think about it: When was the last time a mass Washington rally made a political difference in this country?

It’s a hard question to answer. Rallies still occur, and another will happen Wednesday as thousands are expected to flood the National Mall to commemorate the 1963 March on Washington and its undeniable impact on shaping American attitudes toward civil rights.

It likely will have some of the old-time flavor of momentous events of the past where it felt like history was being made: big crowds, lofty speeches, a common purpose.

But mass gatherings in the Lincoln Memorial’s shadow are no longer the organizer’s favorite method of influencing Washington. In their place is a more sophisticated, even subtle form of mass action.

“It used to be that the way to grab attention was to get a lot of people in one place and get the media to notice,” said Michael Cole-Schwartz of the Human Rights Campaign, which advocates for gay rights.

Today, online advocacy makes it easier to quickly collect supporters and make their views known instantly.

“New technology levels the playing field,” said Matt Kibbe, president and CEO of FreedomWorks, a conservative advocacy group.

The nature of government has changed, too. Unlike 1963, the federal government’s reach is much broader, so zeroing in on specific legislation or elections is seen as a more effective way to influence policy. It makes less sense to pack the National Mall when flooding key members of Congress with emails or phone calls, or holding local rallies, will have more impact.

What may be missing most today, though, is the sense of historic gravitas surrounding the 1960s movements.

“Today’s protests often lack the drama and galvanizing moral clarity that the civil rights and anti-war movement had back in the day,” said Roger Hickey, co-director of the Campaign for America’s Future, a liberal strategy group.

Washington in 1963 was a city where segregation was still a vivid memory, and just across the river was Virginia, where many public schools closed a few years earlier rather than desegregate. The moral stakes were also newly clear to the American masses, since they could now watch segregation dramas played out on TV almost nightly.

Helping to energize the Vietnam protests was a powerful self-interest. Eligible males had to register for the draft. After 1969, they were assigned a lottery number, based on their birthday, placing them in line for the draft.

Huge protests still happen, of course, and organizers believe they still can be effective. But influencing public policy has become more sophisticated. Interest groups have learned to target specific lawmakers, and not always in Washington. Pushing specific legislation can make more sense.

“The system today is incredibly open to external influences,” said Gerard Alexander, associate professor of politics at the University of Virginia.

The tea party experience is seen as Exhibit A. In a study for the American Enterprise Institute, a center-right Washington research group, scholars cited the effectiveness of the group’s April 2009 protests across the nation. An estimated 440,000 and 810,000 people gathered at more than 500 sites.

It worked. The protests “increased turnout in favor of the Republican Party in the subsequent congressional elections, and increased the likelihood that incumbent Democratic representatives decided to retire prior to the elections,” the scholars wrote.

Mass protests, meanwhile, are too hard to control and organize. It takes Herculean logistics – buses, lodging, food, medical care, and working around the threat of bad weather – as well as security requirements that didn’t exist decades ago.

Kibbe recalled big conservative economic justice rallies a few years ago, where people drove from all over the country to Washington.

“You can’t seriously expect people to do that on a regular basis,” he said. “You’ll kill your movement.”

Then there’s the control factor: Nearly everyone has a video recording device, and it only takes one outlier in a crowd to embarrass the movement. And chances are an opposition group will make sure to bring its own protesters, who also will draw attention.

When an estimated 750,000 gathered to urge stricter gun control in the 2000 Mother’s Day “Million Mom March,” an opposition group, the “Second Amendment Sisters,” was also on hand. Though far smaller in numbers, the media took notice.

Social media is arguably more effective. FreedomWorks held its summer “Free the People” event, featuring conservative commentator Glenn Beck and others, July 5 in Salt Lake City. It attracted 16,000 people live – and nearly twice that many online.

Gun control advocates also see huge benefits to online messaging.

“The Internet has totally redefined traditional organizing,” said Pia Carusone, executive director of Americans for Responsible Solutions, a gun control advocacy group. “I think there will always be a role in any movement for large events or rallies. But we’ve found social media to be an even more effective tool in some ways, because we can digitally rally our 500,000 members every single day.”

When the Human Rights Campaign was trying last month to get the Senate Health, Education, Labor and Pensions Committee to approve the Employment Non-Discrimination Act – known as ENDA – it focused on wavering senators. The measure would bar most employers from discriminating on the basis of gender identity or sexual orientation.

A big target was Sen. Lisa Murkowski, R-Alaska. Advocates plastered the state with their message, going door to door and sending emails and postcards. Murkowski voted yes and credited the grassroots push as an influence.

“When I was home over the break, I think it was 1,174 postcards were delivered to my office from Alaskans from around the state in support of ENDA,” Murkowski told reporters at the time. “If you listen to your folks back home, this is important to them.”

Self-interests today are very different. During the Vietnam War “a huge number of people were directly affected,” recalled Hickey of the Campaign for America’s Future.

Today’s issues tend to be less black and white, and it’s often difficult to point to the kind of success civil rights or Vietnam marchers ultimately had. Occupy Wall Street seemed to fizzle, but organizers maintain it helped ignite similar movements across the country.

“Don’t write off mass protests,” said Arlene Holt Baker, AFL-CIO executive vice president. “All of a sudden you see these connections.”

Still, in 2013, protests alone won’t spark the kind of change they did 50 years ago. What also matters is what you can tweet in 140 characters and how far it spreads across the political universe.

“You can’t just march the march,” Baker said. “You have to go home and make changes.”